1. Field of the Invention
The present invention relates to a temperature controlling apparatus that includes a fan rotated to prevent a temperature increase at the surface of a casing that is a controlled object that undergoes various types of processing, a temperature control program, and an information processing apparatus.
2. Description of the Related Art
Conventionally, with an improvement in performance of a large scale integration (LSI) device such as a central processing unit (CPU), a memory, a memory controller, and a graphics chip, mounted on information processing apparatuses such as a personal computer (PC), the performance of the information processing apparatuses have also improved considerably. When heat is generated due to an increase in the temperature of the LSI or the surrounding temperature of the LSI, along with the operation of the LSI, the dissipation of heat to suppress heat generation becomes important. The noise generated due to an increased rotation speed of a fan, which is operated to dissipate heat, is also a problem.
A typical process that has been carried out to reduce the noise and the heat generated by the temperature increase will now be explained with reference to FIG. 11. As shown in FIG. 11, a temperature controlling apparatus includes a fan to prevent an increase in temperature at the surface of a casing, generated by the operation of the LSI in the information processing apparatus. If the temperature at the surface of the casing is increased, the temperature controlling apparatus rotates the fan to dissipate the heat and determines an operating clock frequency of the LSI. The determined operating clock frequency affects the operating performance of a process executed in the LSI. If the operating clock frequency of the LSI is reduced, the temperature increase at the surface of the casing is prevented. Accordingly, the noise in question can be reduced, by reducing the rotation speed of the fan. In the description, the temperature increase at the surface of the casing does not only mean the temperature increase at the surface of the casing, but also means the temperature increase in a space of the casing and the LSI and the like used in the apparatus (hereinafter, “temperature increase at the surface of the casing”).
Explaining more specifically, the temperature controlling apparatus receives the upper limit of the operating clock frequency and the like of the LSI (for example, a CPU that generates a particularly large amount of heat) determined by a user, and changes to the received operating clock frequency (see (1) in FIG. 11). The temperature controlling apparatus then measures a temperature of the LSI that generates heat (see (2) in FIG. 11), determines a fan rotation speed that corresponds to the measured temperature, and changes the rotation speed of the fan (see (3) in FIG. 11). In other words, the temperature controlling apparatus determines the rotation speed of the fan, based on the processing performance of the LSI with the operating clock frequency determined by the user. FIG. 11 is a schematic for explaining a process performed by the conventional temperature controlling apparatus.
In Japanese Patent Application Laid-open No. H11-237931, an information processing apparatus, if the detected temperature in a main body exceeds a predetermined setting value, detects the surrounding noise. The information processing apparatus, if the surrounding noise is equal to or more than the setting value, rotates the fan, and if the surrounding noise is equal to or less than the predetermined setting value, temporarily stops the operating clock frequency. In other words, the information processing apparatus, if the surrounding noise is large, reduces the heat by rotating the fan, because the noise generated by the fan causes a little influence. The information processing apparatus, if the surrounding noise is small, reduces the heat by lowering the performance of the LSI without rotating the fan, because the noise generated by the fan causes a large influence.
In JP-T-2004-516672, if the detected temperature in the main body exceeds the setting value, an audio apparatus measures the output sound and the surrounding noise of the audio apparatus. The audio apparatus, if the temperature and the noise are equal to or more than a predetermined threshold, rotates the fan, and if the temperature and the noise are less than the predetermined threshold, does not rotate the fan. In other words, if the temperature is increased, the audio apparatus reduces heat by rotating the fan, only when the noise of the surroundings and the audio apparatus are large.
However, in the conventional technology as described above, the operating clock frequency of the LSI is excessively reduced, thereby degrading the processing performance of the LSI unnecessarily. Therefore, degradation in performance occurs, for example the LSI that is a controlled object requires a long execution time for the processing.
More specifically, the setting of the operating clock frequency made by the user is not directly related to the noise generated by the rotation of the fan. Accordingly, the performance required for executing the process cannot be satisfied sometimes. The operating clock frequency determined by the user, if not readjusted by the user when the surrounding noise has changed, may be suppressing the LSI operation excessively.
In the Japanese Patent Application Laid-open No. H11-237931 and the JP-T-2004-516672, if the temperature is equal to or higher than a predetermined value, the fan is rotated or stopped, or the performance of the LSI is lowered, depending on the surrounding noise. Accordingly, the fan rotation and the suppression of the LSI operation are off balance, thereby suppressing the operation of the LSI excessively, and degrading the processing performance unnecessarily. As a result, the performance required for executing the process cannot be satisfied.